Method for controlling washing machine

ABSTRACT

Disclosed is a method for controlling a washing machine capable of compensating for a vibration characteristic due to an unbalanced state of a drum, by effectively controlling a ball balancer for compensating for a balance of a rotary body such as a drum. The method includes accelerating the drum having laundry therein for a first time duration (t 1 ) until the drum reaches a reference speed from a stationary state, and decelerating the drum for a second time duration (t 2 ) longer than the first time duration (t 1 ) until the drum reaches the stationary state from the state having the reference speed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.10-2011-0019131, filed on Mar. 3, 2011, which is hereby incorporated byreference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a washing machine, and particularly, toa method for controlling a washing machine capable of compensating for avibration characteristic due to an unbalanced state of a drum, byeffectively controlling a ball balancer for compensating for a balanceof a rotary body such as a drum.

2. Background of the Invention

Generally, a washing machine serves to accelerate a chemical operationof a detergent by forcibly forming a current of washing water inside adrum with using a mechanical force, and serves to enhance a washingeffect by applying a physical operation such as frictions or impacts tolaundry.

FIG. 1 is a view showing a top load type of washing machine inaccordance with the conventional art, in which laundry is put through anupper part of the washing machine under a configuration that a shaft isvertically disposed.

Referring to FIG. 1, the washing machine 10 comprises a cabinet 8 whichforms the appearance, a reservoir (or tub) 1 disposed in the cabinet 8,and a drum 2 rotatably disposed in the reservoir 1. The drum is providedwith a rotatable pulsator 3 at a lower part thereof, and the drum andthe pulsator 3 are driven by being connected to a shaft 5 disposed in avertical direction and connected to a driving motor 7.

Generally, the washing machine has a washing process and a dehydratingprocess. In case of the washing process, the pulsator 3, or the pulator3 and the drum 2 are rotated to rotate laundry and water. In case of thedehydrating process, water is discharged and the drum 2 is rotated witha high speed, thereby removing water from laundry by a centrifugalforce.

During the washing process or the dehydrating process, an unbalanceoccurs due to movements of the drum and a concentrated state of laundry.This may result in noises and vibrations. In order to prevent the noisesand vibrations, the reservoir 1 is suspended at a cabinet by asuspension load 4. And, a ball balancer 9 is provided at an upper partof the drum 2 in a circumferential direction.

The ball balancer 9 serves to compensate for an unbalance of the drumdue to a concentrated state of laundry inside the drum. Referring toFIG. 2, the ball balancer 9 is configured as a ring-shaped racer 9 chaving therein a plurality of metallic balls 9 c. And, fluid 9 b such asoil is filled in the racer 9 a.

When the drum rotates in an unbalanced state due to a concentrated stateof laundry contained in the drum, the ball balancer 9 moves in adirection for compensating for the unbalance by a difference of acentrifugal force. As a result, the ball balancer 9 makes the drumrecover a balanced state.

In case of a dehydrating process, only wet laundry remains in the drum.This may cause the drum to be in a concentrated state. In order toprevent the concentrated state of the drum at an early dehydratingprocess, the balls have to be uniformly distributed in the ball balancerso that the ball balancer can allow the drum to rapidly recover abalanced state.

However, balls provided in a general ball balancer are not rapidlydistributed since fluid is filled in the ball balancer. In this case, ifthe balls are concentrated to one side and laundry is concentrated tothe same direction or a neighboring direction during a washing process,an unbalance of the drum becomes severe at an early dehydrating process.This may increase vibrations. Furthermore, this may cause the reservoir(tub) to collide with the cabinet due to the unbalanced state of thedrum.

SUMMARY OF THE INVENTION

Therefore, an aspect of the detailed description is to provide a methodfor controlling a washing machine capable of allowing a drum to maintaina balanced state, by uniformly distributing balls disposed in a ballbalancer, before the drum starts to rotate during a dehydrating process,etc. when an unbalance may occur.

Another aspect of the detailed description is to provide a method forcontrolling a washing machine capable of reducing vibrations of a drumand preventing a reservoir from colliding with a cabinet, by allowing adrum to maintain a balanced state by controlling a ball balancer.

To achieve these and other advantages and in accordance with the purposeof this specification, as embodied and broadly described herein, thereis provided a method for controlling a washing machine having a drumwhere a ball balancer is installed, the method comprising: acceleratingthe drum having laundry therein for a first time duration (t1) until thedrum reaches a reference speed from a stationary state; and deceleratingthe drum for a second time duration (t2) longer than the first timeduration (t1) until the drum reaches the stationary state from the statehaving the reference speed.

Here, the second time duration (t2) may be longer than the first timeduration (t1) by at least two times.

The first time duration may be 5 seconds, and the second time durationmay be 10 seconds or more. The reference speed may be 80 rpm.

Preferably, the acceleration and the deceleration of the drum may beperformed a plurality of times in a repeated manner. The accelerationand the deceleration of the drum may be repeated with a constant period.After the acceleration and decoration of the drum, a predeterminedstandstill state may be implemented.

As the acceleration of the drum is high, a speed difference betweenlaundry and the ball balancer may increase. This may allow the balls tomove in a is direction for compensating for an unbalanced state of thedrum. Accordingly, the drum may be rapidly accelerated and then slowlydecelerated for uniform distributions of the balls.

Preferably, a dehydrating process may be started after the accelerationand the deceleration of the drum. This may allow the balls inside theball balancer to be uniformly distributed by the acceleration and thedeceleration of the drum, before a dehydrating process of the washingmachine is started.

As the balls are made to be uniformly distributed in the ball balancerbefore a dehydrating process when an unbalance may easily occur,excessive vibrations may be prevented.

According to another aspect of the present invention, there is provideda method for controlling a washing machine having a drum where a ballbalancer is installed, the method comprising: a washing process forperforming a washing operation by supplying washing water into the drum,and by stirring laundry; and a dehydrating process for discharging thewashing water contained in the drum, and separating the washing watercontained in the laundry from the laundry, wherein the dehydratingprocess comprises a discharging step of discharging the washing watercontained in the drum, a balancing step of compensating for a balance ofthe drum, and a dehydrating step of separating the washing water fromthe laundry inside the drum by rotating the drum with a high speed,wherein in the balancing step, the balls disposed in the ball balancerare made to be uniformly distributed by acceleration and deceleration ofthe drum before the dehydrating step.

In the balancing step, the drum having the laundry therein may beaccelerate for a first time duration (t1) until the drum reaches areference speed from a stationary state, and then the drum may bedecelerated for a second time duration (t2) longer than the first timeduration (t1) until the drum reaches the stationary state from the statehaving the reference speed.

In the balancing step, the acceleration and the deceleration of the drummay be performed with a constant period. The acceleration and thedeceleration of the drum may be repeated a plurality of times. After theacceleration and decoration of the drum, a predetermined standstillstate may be implemented.

In the present disclosure, the balls may be made to be uniformlydistributed in the ball balancer before a dehydrating process when anunbalance may easily occur. This may allow the drum to maintain abalanced state.

Furthermore, in the present disclosure, the ball balancer may beefficiently controlled to allow the drum to maintain a balanced state.This may reduce vibrations of the drum, and prevent the reservoir fromcolliding with the cabinet.

Further scope of applicability of the present application will becomemore apparent from the detailed description given hereinafter. However,it should be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate exemplary embodiments andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a schematic view of a washing machine in accordance with theconventional art;

FIG. 2 is a schematic view of a ball balancer of the washing machine ofFIG. 1;

FIGS. 3 and 4 are graphs each showing a change of a rotation speed of adrum according to a first embodiment of the present disclosure; and

FIGS. 5 and 6 are schematic views showing a relative position of ballsdisposed in a ball balancer with respect to laundry according to a firstembodiment of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Description will now be given in detail of the exemplary embodiments,with reference to the accompanying drawings. For the sake of briefdescription with reference to the drawings, the same or equivalentcomponents will be provided with the same reference numbers, anddescription thereof will not be repeated.

In a method for controlling a washing machine having a drum where a ballbalancer is installed according to a first embodiment of the presentdisclosure, the drum having laundry therein is accelerated for a firsttime duration (t1) until the drum reaches a reference speed from astationary state. The, the drum is decelerated for a second timeduration (t2) longer than the first time duration (t1) until the drumreaches the stationary state from the state having the reference speed.

The method is applied to a washing machine having a ball balancer in adrum. The washing machine having a ball balancer in a drum is alreadywell-known, and thus its detailed explanations will be omitted.

The washing machine is provided with a controller (not shown). Thecontroller is configured to determine a rotation speed of the drum, bycontrolling a driving motor which rotates the drum.

The drum is accelerated and decelerated in an alternating manner. Moreconcretely, the drum having laundry therein is firstly accelerated for afirst time duration (t1) until it reaches a reference speed from astationary state. Then, the drum is decelerated for a second timeduration (t2) longer than the first time duration (t1) until the drumreaches the stationary state from the state having the reference speed.

As the acceleration of the drum is high, a speed difference betweenlaundry and the ball balancer may increase. This may allow the balls tomove in a direction for compensating for an unbalanced state of thedrum. As the drum is rapidly accelerated and then slowly decelerated,the balls are uniformly distributed in the ball balancer.

The first time duration (t1) and the second time duration (t2) may beset in various manners. For instance, the second time duration (t2) maybe longer than the first time duration (t1) by at least two times. Thefirst time duration may be 5 seconds, and the second time duration maybe 10 seconds or more. Under these configurations, the balls may beuniformly distributed in the ball balancer by allowing the accelerationto be performed more rapidly than the deceleration.

The reference speed (ω0) may be also set in various manners. Asaforementioned, as a speed difference between laundry and the ballbalancer increases, the balls move in a direction for compensating foran unbalanced state of the drum. Accordingly, it is preferable toincrease the reference speed for a large speed difference.

The driving motor for rotating the drum has to have a limited capacity.For instance, the reference speed may be 80 rpm. The capacity is limitedwith consideration of a performance of the driving motor of a generalwashing machine.

The acceleration and the deceleration of the drum may be repeatedlyperformed a plurality of times. As shown in FIG. 3, the acceleration andthe deceleration of the drum may be periodically performed. The ballsinside the ball balancer move in fluid. Accordingly, the repeatedaccelerations and decelerations may allow the balls to be re-aligned,thereby enhancing a balance of the drum.

After the acceleration and the deceleration of the drum, a standstilltime duration (t3) may be implemented, which is shown in FIG. 4. Due tothe standstill time duration (t3), an excessive load may be preventedfrom being applied to the driving motor of the drum, and the balls maymove in the fluid filled in the ball balancer for a sufficient time.This may allow a position of the balls to be efficiently controlled.

FIGS. 5 and 6 show that positions of the balls inside the ball balancerare re-aligned by controlling the drum of the washing machine.

FIG. 5 shows a state prior to a dehydrating process, in which the balls35 of the ball balancer 30 are positioned at the same side as laundry40. As the drum of the washing machine is accelerated and decelerated,the position of the balls 35 inside the ball balancer is re-alignedduring a dehydrating process as shown in FIG. 5. This may allowcompensation for an unbalance of the drum.

FIG. 6 shows a state prior to a dehydrating process, in which the balls35 of the ball balancer 30 are positioned in a direction facing thelaundry 40, i.e., a direction for compensating for an unbalance of thedrum. As the drum of the washing machine is accelerated and decelerated,the position of the balls 35 inside the ball balancer is nearlymaintained as shown in FIG. 6 during the dehydrating process.

By the operations of the drum and the ball balancer, the position of theballs inside the ball balancer is re-aligned before a dehydratingprocess when an unbalance of the drum may easily occur due to rotationsof the drum. This may allow the drum to maintain a balanced state.

In the preferred embodiment, it is preferable to start a dehydratingprocess after accelerating and decelerating the drum. The reason isbecause it is efficient to perform the acceleration and the decelerationbefore the rotary operation of the drum when an unbalance of the drummay easily occur due to a concentrated state of the laundry.

More concretely, the washing machine has a washing process and adehydrating process. In case of the washing process, washing water issupplied into the drum and the laundry is stirred. And, in case of thedehydrating process, the water washing inside the drum is discharged,and the washing water contained in the laundry is separated from thelaundry.

The dehydrating process includes a discharging step of discharging theto washing water inside the drum, a balancing step of compensating for abalance of the drum, and a dehydrating step of separating the washingwater from the laundry inside the drum by rotating the drum with a highspeed.

In the balancing step, the balls disposed in the ball balancer are madeto be uniformly distributed by acceleration and deceleration of the drumbefore the dehydrating step. More concretely, in the balancing step, thedrum having the laundry therein is accelerated for a first time duration(t1) until the drum reaches a reference speed from a stationary state.Then, the drum is decelerated for a second time duration (t2) longerthan the first time duration (t1) until the drum reaches the stationarystate from the state having the reference speed.

The acceleration and the deceleration of the drum are repeated with aconstant period. The acceleration and the deceleration of the drum areperformed a plurality of times in a repeated manner. After theacceleration and decoration of the drum, a predetermined standstillstate may be implemented. This was aforementioned, and thus detailedexplanations thereof will be omitted.

Before the dehydrating process, the balls inside the ball balancer areuniformly distributed by the acceleration and the deceleration of thedrum. This may allow the drum to maintain a balanced state.

Furthermore, the balls inside the ball balancer are uniformlydistributed before the dehydrating process when an unbalance of the drummay easily occur. This may prevent excessive vibrations from occurringfrom the drum and the reservoir (tub).

The foregoing embodiments and advantages are merely exemplary and arenot to be construed as limiting the present disclosure. The presentteachings can be readily applied to other types of apparatuses. Thisdescription is intended to be illustrative, and not to limit the scopeof the claims. Many alternatives, modifications, and variations will beapparent to those skilled in the art. The features, structures, methods,and other characteristics of the exemplary embodiments described hereinmay be combined in various ways to obtain additional and/or alternativeexemplary embodiments.

As the present features may be embodied in several forms withoutdeparting from the characteristics thereof, it should also be understoodthat the above-described embodiments are not limited by any of thedetails of the foregoing description, unless otherwise specified, butrather should be construed broadly within its scope as defined in theappended claims, and therefore all changes and modifications that fallwithin the metes and bounds of the claims, or equivalents of such metesand bounds are therefore intended to be embraced by the appended claims.

1. A method for controlling a washing machine having a drum where a ballbalancer is installed, the method comprising: accelerating the drumhaving laundry therein for a first time duration (t1) until the drumreaches a reference speed from a stationary state; and decelerating thedrum for a second time duration (t2) longer than the first time duration(t1) until the drum reaches the stationary state from the state havingthe reference speed.
 2. The method of claim 1, wherein the second timeduration (t2) is longer than the first time duration (t1) by at leasttwo times.
 3. The method of claim 2, wherein the first time duration is5 seconds, and is the second time duration is 10 seconds or more.
 4. Themethod of claim 3, wherein the reference speed is 80 rpm.
 5. The methodof claim 1, wherein the acceleration and the deceleration of the drumare performed a plurality of times in a repeated manner.
 6. The methodof claim 5, wherein the acceleration and the deceleration of the drumare repeated with a constant period.
 7. The method of claim 5, whereinafter the acceleration and deceleration of the drum, a predeterminedstandstill state is implemented.
 8. The method of claim 1, wherein adehydrating process is started after the acceleration and thedeceleration of the drum.
 9. A method for controlling a washing machinehaving a drum where a ball balancer is installed, wherein balls mountedin the ball balancer are uniformly distributed by acceleration anddeceleration of the drum before a dehydrating process of the washingmachine.
 10. A method for controlling a washing machine having a drumwhere a ball balancer is installed, the method comprising: a washingprocess for performing a washing operation by supplying washing waterinto the drum, and by stirring laundry; and is a dehydrating process fordischarging the washing water contained in the drum, and separating thewashing water contained in the laundry from the laundry, wherein thedehydrating process comprises: a discharging step of discharging thewashing water contained in the drum; a balancing step of compensatingfor a balance of the drum; and a dehydrating step of separating thewashing water from the laundry inside the drum by rotating the drum witha high speed, and wherein in the balancing step, the balls disposed inthe ball balancer are made to be uniformly distributed by accelerationand deceleration of the drum before the dehydrating step.
 11. The methodof claim 10, wherein in the balancing step, the drum having the laundrytherein is accelerate for a first time duration (t1) until the drumreaches a reference speed from a stationary state, and then the drum isdecelerated for a second time duration (t2) longer than the first timeduration (t1) until the drum reaches the stationary state from the statehaving the reference speed.
 12. The method of claim 11, wherein in thebalancing step, the acceleration and the deceleration of the drum arerepeated a plurality of times.
 13. The method of claim 12, wherein theacceleration and the deceleration of the drum are repeated with aconstant period.